docs: def to_dict(self):
          """
          Convert the existing track to a JSON representation.
          """
          viewconf = json.loads(json.dumps(self.viewconf))
  
          for track in self.tracks:
              if track.position is None:
                  raise ValueError(
                      "Track has no position: {}".format(track.viewconf["type"])
                  )
              viewconf["tracks"][track.position] += [track.to_dict()]
  
          return viewconf